Foundry core making machines have been of many types to form foundry cores to be used inside foundry molds so that a hollow, metal article may be cast. These cores are made from particulate matter and a binder, with the particulate matter usually being sand because of ready availability and economy, and will hereinafter be termed "sand" throughout this patent.
The prior art has known many core making machines wherein the two core boxes move horizontally relative to each other and have a vertical parting line. In other cases, wherein large cores, complex cores, or short production runs are contemplated, it has been customary to make the core in two parts, usually two halves. Each core part has a flat side and then the two core parts are cemented together at the flat sides to form the complete core. Such core making procedure of making them in halves is one wherein usually the core box is laid face upright, rammed with sand and binder mix, covered with a flat plate, inverted in a rollover jolt machine, which then jolts or vibrates the core box and lifts it off the core half. The second core half is made in a similar manner and then one has two half cores each with a flat side resting on a flat plate, usually a metal plate. The binder is somehow cured or hardened but then the problem is to remove each core half from its respective plate, invert one of these core halves, and cement the two core halves together to make a completed core. This becomes more difficult the larger the core halves, and even more difficult where the core is one which is relatively fragile or has thin sections relative to their length or width. It is further complicated wherein the core half does not have a smooth surface opposite that flat surface resting on the plate, because when such core half is inverted it will then not rest evenly on a supporting surface in order to be adhered to the other core half.
Another problem is the jolting or vibrating from the core box; this inherently must remove sand particles from the core half in order to effect removal of the core half from the core box. This means that the core half, and hence the completed core, will be slightly undersize.
Another problem in the prior art machines concerned proper venting of large cores. Sand is favored as a core or mold material because the interstices between the sand particles establish permeability to the gases generated during pouring of the molten metal into the sand mold. Where the core is a large one, the increased length of the core makes it difficult for these gases to escape. Therefore, a vent opening is desired lengthwise of the core, but this is difficult to establish in the usual core making machine.